Developments over the last 10 years in ceramic materials science for dental applications have led to a class of high strength materials (e.g., alumina and zirconia-based ceramics) that potentially provide better fracture resistance and long-term durability than traditional porcelain and other ceramic alternatives. Although superior in terms of mechanical performance (strength, toughness, fatigue resistance), there is an inherent limitation associated with high strength ceramic materials. Bonding of resins to these materials is more difficult than it is for silica-based ceramics. Fortunately, high strength ceramic restorations do not always require adhesive bonding to tooth structure and can be placed using conventional cements that rely only on micromechanical retention. However, conventional cementation techniques do not provide sufficient bond strength for some clinical applications. Good adhesion is important for high retention [1], prevention of microleakage, and increased fracture and fatigue resistance, and is mediated by the use of resin-based cements. Strong resin bonding relies on micromechanical interlocking and adhesive chemical bonding to the ceramic surface [1], and requires a combination of surface roughening and chemical functionalization for effective attachment. A non-destructive, simple method for treating the ceramic surfaces would be very useful in such cases, especially if it would be compatible with existing adhesive bonding techniques (silane + resin cement).

Bonding to traditional silica-based ceramics, generally employing both mechanical and adhesive retention, has been well researched and bond strengths are predictable. A strong resin bond relies on micromechanical interlocking created by surface roughening and on chemical adhesion between the cement and ceramic (by way of silane chemistry). Current techniques are: (1) grinding, (2) abrasion with diamond rotary instruments, (3) surface abrasion with alumina particles, (4) acid-etching (typically hydrofluoric acid [HF]), and (5) a combination of these techniques.

Unfortunately, the chemistry and microstructure of high strength ceramics (specifically alumina and zirconia) differ from those of conventional silica-based materials. These specific ceramics are not easily etched or chemically functionalized using conventional treatments, and require very aggressive mechanical abrasion methods to increase surface roughness, possibly creating strength-reducing surface flaws as a result. Therefore, in order to achieve acceptable cementation, alternative attachment methods are required for alumina and zirconia ceramics.